The prevalence of hypogonadism in nursing home men is about 45%. Osteopenia, fractures, anemia and muscle atrophy are also common in this population. The applicants hypothesize that hypogonadism is a contributory cause to the latter conditions. The proposed study is a double-blinded, placebo-controlled clinical trial of testosterone replacement treatment in 40 hypogonadal nursing home men aged 60-90. Other than advanced age and hypogonadism, other currently operative risk factors for osteopenia are excluded. Clinically evident prostatic disease will also be excluded. After a six month baseline period, the alternating placebo and testosterone periods will each last 18 months. Outcome variables to be measured at two to six month intervals are: regional bone densities, body mineral content, lean body mass, muscle sizes, muscle strength and endurance, activities of daily living, times motor performances, gait and balance abilities, hematocrit, and quality of life indicators. The subjects will be under constant surveillance for adverse behavioral or prostatic reactions to testosterone, which lead to prompt withdrawal from the protocol and appropriate treatment.